There are many demands for a film having a metallic appearance effect on interior and exterior decorative materials for household appliances or buildings. Although such a film is made of a resin and thus economical and easy to handle, it gives us an impression as if it is made from a metal such as expensive stainless steel.
Typically, for this metallic effect, fine cracks should be made on a surface of the film, as those can be seen from a metal such as stainless steel, and they should reflect a shiny metallic color as if the color is generated by its natural characteristics, not merely by its coating.
For example, Korean Laid-open Patent Publication No. 2006-0078530 discloses a high glossy metallic sheet comprising a PET film having hairline patterns, under which a primer layer, an aluminum deposition layer, a urethane adhesive layer and a thermoplastic resin layer are sequentially laminated.
In conventional techniques where the hairlines, i.e., cracks, are formed by passing/scraping a surface of the film through a sandpaper roll, however, lines formed in a longitudinal film direction (also referred to herein as a machine directional hairline) can be formed, but lines formed in a film width direction (also referred to herein as a transverse or horizontal directional hairline) are difficult to form. Accordingly, the cracks or hairlines formed only in the longitudinal direction on the surface of the film lack naturalness as shown in the metal.